1. Appl. Hort., 1 (2) :97-100, July-December, 1999 Effect of defoliation, decapitation and deblossoming on fruit bud differentiation in guava (Psidium guajava L.) Gorakh Singh, A.K. Singh and S. Rajan Central Institute for Subtropical Horticulture, Rehmankhera, P. O. Kakori, Lucknow-227107 Abstract Complete removal of leaves, along with decapitation of shoot was found to be very effective in relation to flower bud differentiation (FBD), while ringing with partial or complete defoliation along with decapitation of shoots was not able to promote FBD. Decapitation of shoots in the presence of leaves formed flower buds with the extent of 44 to 63% and 37.0 to 54.0% in Sardar and Allahabad Safeda, respectively. February, March and April; July, August and September; October, November and December shoots defoliated in May, October and January formed flower buds two months later than the control shoots. Principal component analysis revealed that the time of shoot emergence was the decisive factor for FBD in 1, 2 and 3 months old shoots. The defoliated shoots put forth terminal extension or axillary growth, while in undefoliated ones only terminal growth took place. There is a strong indication that in guava, leaves play favourable role in flower bud formation. Introduction Key words: Guava, defoliation, decapitation, flower bud differentiation. The role of the main apex in inhibiting lateral bud development has been studied in many species (Phillips, 1975), but far fewer investigations have been made regarding the influence of the developing and mature leaves on bud growth. Nevertheless, the inhibitory effects of developing leaves on axillary bud growth have been demonstrated in Phaseolus vulgaris (Field and Jackson, 1974) and Brussels sprouts (Kronenbery, 1973). where, leaf removal resulted in the stimulation of lateral shoot development. It appears that no study has been made so far on the effect of shoot decapitation and ringing on FBD in guava. Likewise, very little work has been reported on the effect of defoliation on FBD. Defoliation and pruning are the main methods in guava to force the axillary bud resulting into shoots on which flowerbuds are formed (Singh et al., 1996). The phenomenon of apical dominance has been explained by both hormone-balance and nutrient theories, but the mechanisms involved are complex and the response of species is so different that many questions remain unresolved (Phiilips, 1975). Singh et al. (1999) observed that in different guava cultivars, time of shoot emergence in has relation with fruit bud differentiation (FBD) and also observed positive correlation between vegetative growth and FBD. Therefore, for accertaining the exact nature of probable factors governing the formation of flower buds, certain treatments such as defoliation, decapitation and ringing were applied to guava shoots, to observe their relative effects on FBD. Materials and Methods The experiment was conducted on eighteen years old trees of Allahabad Safeda and Sardar. A. Defoliation The effect of defoliation was studied under the followingheads: 1. Defoliation of shoots of varying age-groups at a fixed period. 2. Defoliation of the same age Shoots at different periods. 1. Defoliation of shoots of varying ages: A set of two trees each of Allahabad Safeda and Sardar were taken in this experiment. Thirty shoots of each age- group were selected at random, on each tree, and were defoliated in the month of May, October and January. These were also tagged for recording observations on FBD. The same number of untreated shoots in each age-group were kept as control for comparison. 2. Defoliation of the same age shoots at different periods: Thirty shoots of both .the cultivars were tagged in the months of February, March, April,July, August, September, October and December for defoliation in different periods. The selected shoots were defoliated thrice from March 1993 to March 1994. The data matrix of the FBD percent in 1,2 and 3 months old shoots was subjected to Principal component analysis (peA) as suggested by Jeffers (1978). B. Decapitation of shoots For studying the effectofdecapitation on the FBDofthe shoots, the foilowingtreatments were applied. 1. Decapitation of March,April, July, September and December shoots: Generally it is understood that the terminal buds exert an inhibitory effect on the axillary buds which remain dormant in its
Transcript
1. Appl. Hort., 1(2) :97-100, July-December, 1999
Effect of defoliation, decapitation and deblossoming on fruit buddifferentiation in guava (Psidium guajava L.)
Gorakh Singh, A.K. Singh and S. Rajan
Central Institute for Subtropical Horticulture, Rehmankhera, P. O. Kakori, Lucknow-227107
AbstractComplete removal of leaves, along with decapitation of shoot was found to be very effective in relation to flower bud differentiation(FBD), while ringing with partial or complete defoliation along with decapitation of shoots was not able to promote FBD. Decapitationof shoots in the presence of leaves formed flower buds with the extent of 44 to 63% and 37.0 to 54.0% in Sardar and Allahabad Safeda,respectively. February, March and April; July, August and September; October, November and December shoots defoliated in May,October and January formed flower buds two months later than the control shoots. Principal component analysis revealed that the timeof shoot emergence was the decisive factor for FBD in 1, 2 and 3 months old shoots. The defoliated shoots put forth terminal extensionor axillary growth, while in undefoliated ones only terminal growth took place. There is a strong indication that in guava, leaves playfavourable role in flower bud formation.
The role of the main apex in inhibiting lateral buddevelopment has been studied in many species(Phillips, 1975), but far fewer investigations havebeen made regarding the influence of the developingand mature leaves on bud growth. Nevertheless, theinhibitory effects of developing leaves on axillary budgrowth have been demonstrated in Phaseolusvulgaris (Field and Jackson, 1974) and Brusselssprouts (Kronenbery, 1973). where, leaf removalresulted in the stimulation of lateral shootdevelopment. It appears that no study has beenmade so far on the effect of shoot decapitation andringing on FBD in guava. Likewise, very little workhas been reported on the effectof defoliationon FBD.Defoliation and pruning are the main methods inguava to force the axillarybud resulting into shoots onwhich flowerbuds are formed (Singh et al., 1996). Thephenomenon of apical dominance has been explainedby both hormone-balance and nutrient theories, butthe mechanisms involved are complex and theresponse of species is so different that many questionsremain unresolved (Phiilips, 1975). Singh et al. (1999)observed that in different guava cultivars, time ofshoot emergence in has relation with fruit buddifferentiation (FBD) and also observed positivecorrelation between vegetative growth and FBD.Therefore, for accertaining the exact nature ofprobable factors governing the formation of flowerbuds, certain treatments such as defoliation,decapitation and ringing were applied to guava shoots,to observe their relative effects on FBD.
Materials and MethodsThe experiment was conducted on eighteen years oldtrees of Allahabad Safeda and Sardar.
A. DefoliationThe effect of defoliation was studied under thefollowingheads:
1. Defoliation of shoots of varying age-groupsat a fixed period.
2. Defoliation of the same age Shoots atdifferent periods.
1. Defoliation of shoots of varying ages: A set oftwo trees each of Allahabad Safeda and Sardar weretaken in this experiment. Thirty shoots of each age-group were selected at random, on each tree, andwere defoliated in the month of May, October andJanuary. These were also tagged for recordingobservations on FBD.The same number of untreatedshoots in each age-group were kept as control forcomparison.
2. Defoliation of the same age shoots at differentperiods: Thirty shoots of both .the cultivars weretagged in the months of February, March, April,July,August, September, October and December fordefoliation in different periods. The selected shootswere defoliated thrice from March 1993 to March1994. The data matrix of the FBD percent in 1,2 and3 months old shoots was subjected to Principalcomponent analysis (peA) as suggested by Jeffers(1978).
B. Decapitation of shootsFor studying the effectofdecapitationon the FBDof theshoots, the foilowingtreatments were applied.
1. Decapitation of March,April, July, Septemberand December shoots: Generally it is understoodthat the terminal buds exert an inhibitory effect onthe axillary buds which remain dormant in its
98 Journal of Applied Horticulture
presence. Shoots of Allahabad Safeda and Sardarwere used for this treatment to see how far theremoval of the terminal buds helped in the activationof axillary buds with regard to FBD. The presentinvestigation gives a detailed account of the effect ofdecapitation for which 50 March, April, July,September and December shoots, each of AllahabadSafeda and Sardar were decapitated after two monthsfrom the date of their emergence and the samenumber of shoots were kept as control.
2. Decapitation followed by ringing and partial orcomplete defoliation, and ringing followed bydefoliation only: In the defoliation treatments, therewas indication of some important role played by theleaves in the fruit bud differentiation. It was,therefore, planned to combine decapitation anddefoliation of shoots with ringing. Experiments were,therefore, laid out to asses the importance of leaves ininducing axillary flower buds in the decapitatedshoots. Some shoots were also ringed to see thebehaviour of the terminal buds in the absence ofleaves. For this study, there were four treatmentsapplied.
i. Shoots decapitated, ringed and completelydefoliated above the ring.
ii. Shoots decapitated, ringed and partiallydefoliated with two leaves on each shoot
iii. Shoots ringed and completely defoliatediv. Completely defoliated and decapitated.
The treatments were given in the second week ofMay,with 50 shoots on each tree ofAllahabad Safedaand Sardar under each treatment.
ResultsDefoliation of shoots of varying ages: Flower budsdifferentiated on all the defoliated shoots in both thecultivars, irrespective of the age group, but thetreated shoots formed flower buds about a monthlater than the control. It is clear from Table 1 thatFebruary, March and April shoots defoliated in Mayformed flowerbuds i.e. 43.3 and 36.6 % as comparedto 63.3 % and 46.6 % in control in Sardar andAllahabad Safeda, respectively. July, August andSeptember defoliated shoots formed flower buds i.e.33.3 and 30.0 % in Sardar and Allahabad Safeda,respectively as compared to 43.3 and 23.3 % undercontrol of respective cultivars.
Defoliation of the same age shoots at differentperiods: February shoots defoliated in May; Aprilshoots in May, June and July; August shoots inSeptember, October and November; Septembershoots in October, November and December andOctober shoots in November,December and Januarydid not formed any flowerbud which was contrary tothe behaviour of the control shoots (Table2). PercentFED was found to be better when February shootsdefoliated in the month of March i.e. 53.0 and 49.0% in Sardar and Allahabad Safeda, respectively.
However, control shoots showed high percentage ofFBD from March shoots i.e. 60.0 and 70.0 % inrespective cultivars.Table 1. Effect of defoliation of shoots of varying ageson FBD in guava cvs. Sardar and Allahabad Safeda
Particulars of Number of Percent of shoots differen-Shoots Shoots un- tiating into fruit buds
September October (27.0) 0.0November : 0.0December 0.0November (37.0) 0.0December 0.0January 0.0
December January (39.0) 14.0February 13.0March 18.0
(70.0) 49.013.02.0
(40.0) 31.09.07.0
(32.0) 0.00.00.0
(20.) 17.09.03.0
(46.0) 0.00.00.0
(58.0) 0.00.00.0
(31.0) 0.00.00.0
(63.0) 17.012.021.0
March
April
July
August
October
Figures in parenthesis refer to control
Decapitation of shoots: The shoots, decapitated inMarch, producedmaximum flowerbuds i.e..63.0 and54.0 % as compared to 60.0 and 38.0 % under controlin Sardar and Allahabad Safeda, respectively(Table3).Allthe decapitated September and Decembershoots inboth the cultivars produced only vegetative growth,
Defoliation, decapitation and deblossoming effects on fruit bud differentiation in guava 99
whereas non-treated shoots differentiated into flowerbuds i.e. 32.0 and 53.0 % in respective cultivars.
It is clear from Table 4 that shoot decapitationfollowed by ringing-and partial ringing followed bydefoliation had almost negligible influence on flowerbud formation in both the cultivars. Whilecompletely defoliated and decapitated shoots formedfruit buds i.e. 59.0 and 48.0 % in Sardar andAllahabad Safeda.
Table 3. Behaviour of shoots, decapitated in differentmonthsParticulars ofshoots
Period oftreatment
Shoots differentiating into fruitbuds (%)
Sardar Allahabad SafedaMarch May 63.0 (60.0) 54.0 (38.0)April June 44.Q (21.0) 37.0 (27.0)July September 20.0 (39.0) 13.0 (21.0)September November 0.0 (27.0) 0.0 (49.0)December February 0.0 (32.0) 0.0 (53.0)
X2 = 22.44, 4 d.f., p=0.0002; Figures in parenthesis refer to control
Table 4. Behaviour of the decapitated, ringed anddefoliated shoots; decapitated, ringed and partiallydefoliated shoots, ringed and defoliated shoots
Treatments Shoots differentiatinginto fruit buds (%)
Sardar AllahabadSafeda
A Shoot decapitated, ringed and 0.0 0.0completely defoliated
B Shoots decapitated, ringed 0.0 0.0and partially defoliated
C Shoots ringed and completely 0.0 0.0defoliated
D Completely defoliated and 59.0 48.0decapitated
• Sardar ••• Allahabad Safeda2.01.5 e ~
Dec Dec1.00.5 t5 ts ~ Jul
e MarU 0 OO~ .."_.l.~pr -c,
-0.5 IS'~S~; Jul A A Mar
-.10I"
-1.5 Feb
-2.0 Feb eA
-1.5 -1.0 -0.5 0 0.5 1.0 1.5 2.0PC I
Fig. 1. Two dimensional ordination of first two PC scores extractedseparately from data matrix for Allahabad Safeda and Sardar
DiscussionUnder given climatic conditions, the number offruiting primordias which develop in a shoot buds isinfluenced by cultivar and nature of treatment. Boththe cultivars under study vary widely in their FBDability. Studies of various research workers have alsoshown that the proportion of buds in which FBDoccurs all along the length of shoot, varies with thefruit species (Phillips, 1975).The results indicate thatdefoliated shoots of varying ages in both the varietiesform flower buds less in number as compared tocontrol shoots. While the defoliation of the same ageshoots (shoots of August, September and October) atdifferent time did not form any flower bud, certainpercentage of February, March July and Decemberdefoliated shoots produced flower buds.' However,this behaviour is not easy to interpret since the effectof defoliation depended very much on the influenceexerted by the presence of the main apex. Oneinterpretation of this effect is that the leaves aremajor source of nutrition and hormoriee-necessaryfor the development of axillary shoots in guava onwhich flower buds are formed (Singh et al., 1999).The present finding confirms the observations ofThomas (1983) in Brussels sprouts and Singh (1961)in mango. However, most of the results do notsupport this contention, rather indicates that theleaves produce substance(s) inhibitory to bud growthor they deprive the buds of substances necessary forgrowth.
Per cent FBD in the shoots defoliated after first,second and third month of emergence were used asthree variables for principal component analysis. Theanalysis revealed (Fig. 1) that the time of shootemergence was decisive for FBD in 1,2 and 3 monthold shoots. The figure clearly shows that shootsemerging in April, May, June and September are notfavourable for FBD whereas shoots emerging in themonths of February, March, July and December aresuitable for FBD. This shows that FBD is moredependent on season as compared to variety anddefoliation technique. It seems that variety anddefoliation treatment has limited role in explainingthe variability in FBD data. It is also indicated thatshoot of both the varieties under. study are of similarnature in their behaviour with regard to response todefoliation.
Results on the decapitation show that the responseto decapitation is different in Sardar and Allahabad.Sixty per cent and fifty four per cent of Sardar andAllahabad Safeda shoots differentiated flowerbuds asa result of decapitation of March shoots. Thisemphasises the inhibitory effect of the terminal budson the dormant axillary buds of the shoots. It isevident from the study that the ringed, decapitatedand defoliated shoots in both the varieties fail to formflower buds. However,' in such shoots axillaryvegetative buds are formed in both the varieties.There results lead one to believe that the presence ofleaves is essential for the transmission of the flower'bud forming substances to induce axillary flowerbuds. Defoliation and decapitation (combined) hadsignificant effect on flower bud formation. Since
100 Journal of Applied Horticulture
Referencedefoliation enhances the out growth of axillary budsin ringed and decapitated shoots, the suggestion ofKronenberg (1973) that the leaves produce growthinhibitor(s) which may be transported into theaxillary buds and thus retarding growth, seems valid.
The chi-square test performed to determine whetheror not to reject the idea that with regard to FBD, thevariety and defoliation treatment are independent,revealed that FBD is dependent on varying age of theshoots not on the variety. Since the p-value is 0.25,we cannot reject the hypothesis that variety andvarying age of the shoots are independent.
In our study, how the presence of leaves initiate FBDin all the decapitated and defoliated shoots and howit fails to induce FBD in the majority of similarshoots of September and December is not clearlyunderstood. Further, probably the optimum set ofconditions required for axillary flower bud formationpurely vary with different fruit crops.
AcknowledgementThe authors are grateful to Dr. S.S. Negi, Director,Central Institute for Subtropical Horticulture for hiskeen interest in the present study and providingnecessary facilities. ,
Field, R.J. and D.l. Jackson, 1974. A hormone balancetheory of apical dominance, In: R.L. Bieleski, A.R.Ferguson and M.M. Cresswell (Editors). Mechanisms ofRegulation in Plant Growth. Bulletin 12. The Royal So-ciety of New Zealand, Wellington pp 655-65.
Jeffers, John N.R. 1978. An introduction to system analy-sis : with ecological application. Edward Arnold, Lon-don
Kronenbery, H.G. 1973. Grwoth of side shoots in Brussel'ssprout plants as influenced by GA, and defoliation.Neth, J. Agric. Sci., 21:124-128.
Singh, Gorakh, D. Pandey, S. Rajan and A.I<. Singh, 1996.Crop regulation in guava through different crop regu-lating treatments. Fruits, 51:241-46.
Singh, Gorakh, S. Rajan, D. Pandey and A.I<. Singh, 1999.FBD and contribution of different flushes towards an-nual yield of guava (Psidium guajava L.). J. Appl. Hori.,1(1):19-23.
Singh, R.N. 1961. Studies in the differentiation and devel-opment of fruit bud in Mango~angifera indica L.) V.Effects of defoliation, decapitation and deblossoming onfruit bud differentiation. Ind. J. Hort., 18: 1-11.
Thomas, T.H. 1983. Effects of decapitation, defoliationand stem gird ling on axillary bud development in Brus-sels sprouts, Scieniia Hortic. 20:45-5l.
